The invention relates to a flow cell, in particular for analyzing or/and synthesizing substances, having at least one storage zone which is connected to a duct for transporting fluid from, into, or/and through the storage zone, wherein the duct has a duct zone that is delimited by a substrate and by a flexible film which is connected to the substrate, in which duct zone the duct is closed off and at a predetermined breaking point is openable while deflecting the film.
A flow cell of such type in which the duct is connected to a storage chamber that is to be emptied by way of the duct is derived from WO 2009/071078 A1. The storage chamber is formed by a thermoformed zone of the otherwise planar film that delimits the duct zone. The film is composed of an aluminum layer having a plastics coating that faces the internal side of the storage chamber. Outside the storage chamber and the duct zone, and at the predetermined breaking point, the film is adhesively bonded or/and welded to a planar surface of the substrate or to a further film that covers the latter.
The predetermined breaking point that is established by welding or/and adhesive bonding between the plastics coating of the film and the planar surface of the substrate, in terms of the planar extent of the former, is capable of being metered only with great difficulty. Influences caused by variations result above all from the behavior of the plastics coating of the film during welding, from the distribution of the temperature generated by a welding tool, from the achievable welding track width of approx. 1 mm, from the accuracy in positioning the welding tool and thus from the reproducibility of the spacing of the predetermined breaking point from the storage zone. The force required for rupturing the predetermined breaking point varies accordingly in an undesirable manner.